1. Field of the Invention
The present invention generally relates to a vehicle on-board unit. More specifically, the present invention relates to a vehicle on-board unit that is configured and arranged to report an estimated time of arrival and an accuracy indicator for the estimated time of arrival from historical estimated time of arrival information.
2. Background Information
Recently, vehicles are being equipped with a variety of informational systems such as navigation systems, Sirius and XM satellite radio systems, two-way satellite services, built-in cell phones, DVD players and the like. These systems are sometimes interconnected for increased functionality. Various informational systems have been proposed that use wireless communications between vehicles and between infrastructures, such as roadside units. These wireless communications have a wide range of applications ranging from crash avoidance to entertainment systems. The type of wireless communications to be used depends on the particular application. Some examples of wireless technologies that are currently available include digital cellular systems, Bluetooth systems, wireless LAN systems and dedicated short range communications (DSRC) systems.
Dedicated short range communications (DSRC) is an emerging technology that has been recently investigated for suitability in vehicles for a wide range of applications. DSRC technology will allow vehicles to communicate directly with other vehicles and with roadside units to exchange a wide range of information. In the United States, DSRC technology will use a high frequency radio transmission (5.9 GHz) that offers the potential to effectively support wireless data communications between vehicles, and between vehicles, roadside units and other infrastructure. The important feature of DSRC technology is that the latency time between communications is very low compared to most other technologies that are currently available. Another important feature of DSRC technology is the capability of conducting both point-to-point wireless communications and broadcast wireless messages in a limited broadcast area.
One example of an application of wireless communications in a vehicle informational system is an off-board dynamic navigation system. In the off-board dynamic navigation system, a desired destination is entered by a user through HMI (human-machine interface) of a vehicle on-board unit. Then this desired destination is transmitted to an external navigation server through wireless communications. The navigation guidance service is derived from an external navigation server, which functions as a driving route assistance service information center. The wireless system of the vehicle on-board unit receives route information from the navigation service of the external service server. The route information is communicated to the driver through the HMI of the vehicle on-board unit such as a display or audio. In particular, in such off-board dynamic navigation system, the external service server receives the destination (e.g., address, point of interest) from the vehicle on-board unit via some mode of wireless communication (e.g., cellular, WiMax, WiFi, DSRC) and provides an initial heading. As the vehicle passes a roadside unit, the vehicle on-board unit receives updated route instructions based upon the latest external data (e.g., traffic, construction) transmitted from the external service server. Thus, the off-board dynamic navigation system makes it possible to always have the latest map information and the most suitable route guidance information. Moreover, the large-capacity storage device required for conventional on-board navigation is not needed when the external service server is used for providing the navigation service.
These external navigation servers sometimes provides an estimated time of arrival (ETA) for the selected route. Typically, the estimated time of arrival (ETA) is calculated using an algorithm that takes into account various road characteristics such as distance, road speed limits, traffic lights etc. While an estimated time of arrival calculated by this method can be quite helpful, the estimated time of arrival is often inaccurate because it does not consider other factors such as time of day (rush hour or non-rush hour), traffic congestion, road construction, etc.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved vehicle on-board unit. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.